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FRIDAY, July 25 (HealthDay News) -- Anyone who has avoided Monday morning weigh-ins knows this unalterable truth: Weekends are not a dieter's friend.

Now, researchers have some science to back up dieters' complaints about weekends being their undoing: Most people do eat more on the weekend, even when they're trying to lose weight.

"Weekend indulgences can wreak havoc on weight control, either causing our weight to increase or if we are following a diet to lose weight, can hinder our weight loss efforts," said study author Susan Racette, an assistant professor at Washington University in St. Louis. The research was published online recently in the journal Obesity.

Racette and her colleagues followed 48 men and women for a year, trying to determine the effects of weekends on weight loss efforts.

They assigned the participants, who ranged from being healthy weight to being nearly obese, to one of three groups: The controls did not change diet or activity levels; the calorie-restriction group reduced intake by 20 percent, and the physical activity group increased physical activity every day by 20 percent. Participants kept food diaries and wore devices to measure activity.

But even before the intervention started, Racette gathered data -- on daily weight, food intake and physical activity -- and found that the weekends were for indulging.

"At baseline, before they were supposed to be following a diet or exercise plan, we found on weekends, people gained weight," she said. During the week, the weight would decline. But the weekend effect was strong. "If you translate it out to a year, it could have increased weight by 9 pounds."

Before the intervention, participants ate an average of 2,257 calories on Saturday compared to just 2,021 during the week. But the average activity on weekends overall didn't differ much from average weekday activities. So, it was the food, not the lack of activity, that was to blame, Racette said.

Racette monitored the participants for a year after they started the intervention, and the weekend indulgences continued. The calorie restriction group stopped losing weight on weekends, while the physical activity group gained slightly (about .17 pounds). There were not significant weight changes in the controls on weekends.

Weekend indulgences help explain the slower-than-expected weight loss of many dieters, Racette said. "There is less structure on the weekend for a lot of people, and that can wreak havoc," she said. "A little indulgence turns into a big indulgence. Being vigilant on the weekends is really important for people either trying to lose weight or maintain a weight loss," she said.

More information

For more on dieting, American Dietetic Association  .

FRIDAY, July 25 (HealthDay News) -- Men over 40 may want to avoid iced tea and start hitting the lemonade if they wish to lower their risk of kidney stones, according to experts.

Kidney stones, crystals that develop in the kidneys or the tubes that carry urine from the kidney to the bladder, affect 10 percent of the U.S. population, and men run a four times greater risk than women of developing them. The chance of forming kidney stones rises steeply after the age of 40.

Oxalate, a key chemical in the formation of kidney stones, comes in high concentrations in iced tea.

"For many people, iced tea is potentially one of the worst things they can drink," John Milner, an instructor in the department of urology at Loyola University Chicago Stritch School of Medicine, said in a news release. "For people who have a tendency to form kidney stones, it's definitely one of the worst things you can drink."

The failure to stay hydrated is a common cause of kidney stones. Summertime heat and humidity, which causes excessively sweating and dehydration, combined with an marked increase in iced tea consumption in the United States, raises the risk of kidney stones during this time of year.

The Tea Association of the U.S.A. reports that Americans consume almost 1.91 billon gallons of iced teas a year, a dramatic rise given the belief that the beverage is healthier than other alternatives such as soda and beer.

Milner said drinking water is the best way to stay properly hydrated. If one is prone to developing kidney stones, though, flavoring water heavily with lemon or drinking lemonade may help.

"Lemons are very high in citrates, which inhibit the growth of kidney stones," Milner said. "Lemonade, not the powdered variety that uses artificial flavoring, actually slows the development of kidney stones for those who are prone to the development of kidney stones."

Other foods containing high concentrations of oxalates that people prone to kidney stones should avoid include spinach, chocolate, rhubarb and nuts. Going light on salt consumption, reducing the amount of meat consumed, drinking several glasses a water a day, and eating foods high in calcium, which counteract any oxalates the body absorbs, also helps.

More information

The National Kidney and Urologic Diseases Information Clearinghouse has more about kidney stones.

FRIDAY, June 13 (HealthDay News) -- Just sniffing that first hot cup of coffee in the morning may help ease some stresses you might be feeling, a South Korean trial indicates.

When rats inhaled the aroma of roasted coffee beans, a number of genes were activated, including some that produce proteins with healthful antioxidant activity, the researchers reported.

"The meaning of it is not totally clear yet," said Dr. Peter R. Martin, director of the Institute of Coffee Studies at Vanderbilt University. "What it does show is that coffee smells do change the brain to some degree, and it behooves us to understand why that is happening."

The findings, from a team led by Han-Seok Seo at Seoul National University in South Korea, were expected to be published in the June 25 issue of the Journal of Agricultural and Food Chemistry.

The experiment was done with laboratory rats, some of whom were stressed by being deprived of sleep. The researchers did detailed genetic studies that showed the activity of 11 genes was increased and the activity of two genes was decreased in the rats that smelled the coffee, compared to those who did not. In effect, the aroma of the coffee beans helped ease the stress of the sleep-deprived rodents.

The experiment provides "for the first time, clues to the potential antioxidant or stress-relaxation activities of the coffee bean aroma," the researchers wrote.

And they added, "These results indirectly explain why so many people use coffee for staying up all night, although the volatile compounds of coffee beans are not fully consistent with those of the coffee extracts. In other words, the stress caused by sleep loss via caffeine may be alleviated through smelling the coffee aroma."

"They used the latest in technology to see how brain expression of RNA changed," Martin said. RNA is the molecule that carries out the instructions encoded in genes. "This is just the beginning of a very interesting line of investigation," he added.

The aromatic compounds responsible for coffee's odor may be antioxidants, "but they are not the same as the major antioxidants that are in the drink," said Joe A. Vinson, a chemistry professor at the University of Scranton in Pennsylvania.

Chemically, the antioxidants in liquid coffee are polyphenols, Vinson said. Those in the aroma are heterocycle compounds containing sulfur or nitrogen atoms.

"There are two ways to get things into your system, and the quickest way is to smell them," Vinson said. "Caffeine gets into the brain via the blood stream. Here, aromatic molecules get into the brain through the olfactory system. The levels in the air are parts per million, so obviously these are minor components in the air. But they are doing something."

Previous studies have shown that coffee consumption can reduce depression and suicide risk, as well as relieve stress, effects generally attributed to the caffeine in coffee, the researchers noted. But while some 900 compounds that float away from the bean have been identified, this is the first study to assay their possible effects, they added.

It's too early to recommend that people feeling stress sniff coffee to ease their way, Martin said. But, he added, "people who don't even drink coffee are fascinated by the odor of it. Ever since my little boy was two years old, he has loved the odor of coffee. I have always thought that coffee has some mystic quality, and there is some deep historical basis for it."

More information

The latest on coffee health research is available from the Coffee Science Information Centre  .

THURSDAY, June 12 (HealthDay News) -- A session of moderate aerobic exercise can help reduce anxiety and improve the quality of sleep for insomnia patients, according to a Brazilian study. Heavy aerobic or moderate strength exercises don't have the same effect.

Researchers at the Federal University of Sao Paulo divided 28 women and eight men with primary chronic insomnia into three exercise groups -- moderate aerobic, heavy aerobic, and moderate strength -- and one control group.

After the exercise session, those who did moderate aerobic exercise showed reductions in sleep onset latency (54 percent) and wake time (36 percent) and increases in total sleep time (21 percent) and sleep efficiency (18 percent). They also showed a 7 percent decrease in anxiety.

"These findings indicate that there is a way to diminish the symptoms of insomnia without using medication," study author Giselle S. Passos said in a prepared statement.

"This is the first study to look at the importance of using physical exercise to treat insomnia and may contribute to increased quality of life in people with one of the most important kind of sleep disorders around the world," Passos said.

The findings were presented Wednesday at the annual meeting of the Associated Professional Sleep Societies, in Baltimore.

More information

The American Academy of Family Physicians has more about insomnia  .